Conventionally, as an articulated mechanism for a prosthetic hand or a robotic hand (collectively referred to as “hand”), articulated mechanisms capable of carrying out substantially the same movements as human digital joints have been developed. For example, one of such conventional articulated mechanisms is a mechanism in which a plurality of digital parts (corresponding to respective bones of a finger, referred to as link members) are rotatably joined each other and each of the joined digital parts is driven by a driving means so that the respective digital parts are rotated at desired degrees (see, for example, Patent documents 1, 2, 3 and 4). As the driving means, a linear actuator, a motor, a fluid-pressure-operated actuator, or the like may be used.
On the other hand, when a human hand grasps an object, a plurality of fingers are flexed in respective different shapes such that the respective fingers touch the surface of the object with substantially the same pressures. For carrying out such movement with the aforementioned conventional articulated mechanism, it is required to provide driving means for driving each finger independently so that the respective fingers can be flexed at different angles (see, for example, Patent document 1) or alternatively, it is required to diverge force by single driving means into the plural fingers (see, for example, Patent document 2).